Do you think this is a fair price on this Mustang?

If it was a v8 no, but you have the crappy v6. Look your car up on kbb and see

Have you done the KBB and NADA values on it? Does it have a clear title? You might want to add some more descriptions to your ad as well. Sometimes that helps. I know my car sold in a day because it was priced $100 below KBB and everyone told me that it had such a great description that it made it easy to make the decision to come see it. It also may depend on the area that you live in. If it's more rural then it may be harder to get someone out of the way to come see it and get it.

I don't think it's a good deal, at all.

You can buy a brand new base automatic 2014 Mustang for $21,500 and it comes with the 305HP V6.

This one is 4 years old and only has 210HP (Ford changed the engine for 2011).

Definitely. I paid that much for a 2010 dodge avenger with 40k miles. It's not even a sports car.